Smoke suppressant compositions for petroleum fuels

ABSTRACT

The invention disclosed herein is a smoke suppressant additive comprising an ether, a Group IIA metal carboxylate and a Group IIB metal carboxylate. A preferred fuel additive is a mixture of an alkyl ether of ethylene glycol and barium and zinc alkanoates wherein the weight ratio of ether to total carboxylates if from about 4:1 to 1:1. A further improved additive is obtained when a Group IIA metal sulfonate, especially a barium alkaryl sulfonate, is incorporated into the carboxylates-ether additive mix. An additive mixture having a ratio of about 1 to 2 parts ether and 1 to 2 parts of barium alkaryl sulfonate per part barium and zinc alkanoates, is particularly suitable.

[ 72] Inventor Elmer J. lBadin lllightstown, NJ. [21] Appl. No. 779,220 [22] Filed Nov. 26, 1968 [45] Patented Oct. 26, 1971 [73] Assignee Cities Service Oil Company Tulsa, Ollrln. Continuation-impart of application Ser. No. 694,819, Jun. 2, 1968.

[54] SMOKE SUPPRESSANT COMPOSIITIIONS lFOlR PETROLEUM lFUlElLS 15 Claims, No Drawings [52] 11.1.8. (31 14/66, 44/68, 44/70, 44/76 [51] lint. 1C1 (31011/18, C101 1/30 [50] lField of Search 44/57,66, 68, 70, 76, 77

[56] References Cited UNITED STATES PATENTS 3,501,279 3/1970 Allen et a1. 44/70 2,221,839 11/1940 Lipkin 44/57 X 2,560,542 7/1951 Bartleson et a1. 44/68 X 2,763,537 9/1956 Barusch et a1. 44/77 X 3,085,866 4/1963 Gay et a1 44/57 3,348,932 10/1967 Kukin 44/57 X 3,389,978 6/1968 Mann et a1 44/57 3,415,632 10/1968 Rechberger 44/57 X 3,437,465 4/1969 Le Suer 44/57 X FOREIGN PATENTS 1,003,746 9/1965 Great Britain 44/77 661,907 2/1965 Belgium 44/76 Primary Examiner- Daniel E. Wyman Assistant ExaminerW. J. Shine Attorney-J. Richard Geaman ABSTRACT: The invention disclosed herein is a smoke suppressant additive comprising an ether, 21 Group [IA metal carboxylate and a Group [18 metal carboxylate. A preferred fuel additive is a mixture of an alkyl ether of ethylene glycol and barium and zinc alkanoates wherein the weight ratio of ether to total carboxylates if from about 4:1 to 1:1. A further improved additive is obtained when a Group 11A metal sulfonate, especially a barium alkaryl sulfonate, is incorporated into the carboxylates-ether additive mix. An additive mixture having a ratio of about 1 to 2 parts ether and l to 2 parts of barium alkaryl sulfonate per part barium and zinc alkanoates, is particularly suitable.

SMOllilE SUPPRESSANT COMIPOEHTIIONS l Ollt lPlE'llllkOlLlEUll/ll FUELS CROSS-REFERENCES TO RELATED APPLICATIONS This application is a continuation-in-part of my copending application, Ser. No. 694,819 filed Jan. 2, 1968.

BACKGROUND OF THE lNVENTlON This invention relates to new fuel additives. in particular, it relates to new fuel additives which reduce the smoke and soot formed during the operation of internal combustion engines, especially compression ignition engines.

The petroleum industry has encountered serious problems in supplying the demand for middle distillate and heavy residual fuel oils suitable for injecting into compression ignition engines, which will not contribute materially to the pollution of the atmosphere through smoke and soot production. Coupled with this specific need for a diesel fuel mixture with reduced smoking characteristics, there is also an urgent need for liquid hydrocarbon fuel mixtures having improved combustion characteristics for spark ignition and jet engines.

Attempts have been made to reduce the visible, black smoke and soot present in exhaust emissions formed during the oxidation of liquid hydrocarbon fuels. By way of example, certain metallic smoke suppressant mixtures have been employed in compression ignition engines, but objections to these mixtures are that they leave deposits in engine crankcases as a result of blowby from cylinders, can be expensive to produce and package, and can form undesirable combustion products in proportion to their content of metal. Further it has been additionally proposed to incorporate various materials into fuels to inhibit their soot, sludge and clogging tendencies. However, some of these materials have proven susceptible to emulsification upon storage and, in certain cases have shown a tendency to lower the Cetane Number of diesel fuels, or reduce the Octane Number of gasoline, while others have reduced the stability of fuel to oxidation during storage. Further, these and other additives have not generally imparted other beneficial properties to fuels, such as corrosion protection for engine surfaces, or surfactant properties to help cleanse injectors in diesel engines and provide a more uniform spray pattern therein in addition to smoke and soot suppressing action.

Accordingly there exists an urgent need to produce a multifunctional hydrocarbon fuel additive, capable of suppressing smoke and soot formed by operating internal combustion engines and otherwise improving combustion, free of the side effects and deficiencies of the prior art.

SUMMARY OF THE INVENTION It is an object of this invention to provide a liquid hydrocarbon fuel additive and, in particular, a diesel fuel additive which can reduce the visible black smoke and soot formed during operation of internal combustion engines.

It is an object of this invention to provide a smoke and soot suppressing fuel additive which produces a minimum of ash upon combustion.

it is a further object of this invention to provide a smoke suppressant fuel additive which imparts improved oxygen stability to a base fuel.

It is an additional object of this invention to provide a fuel additive, which when mixed with a fuel, does not adversely effect Cetane Number and water tolerance characteristics of the base fuel, yet which reduces visible smoke and soot formed during combustion ofthe fuel.

it is another object of this invention to provide a fuel additive which imparts corrosion inhibiting tendencies to fuel mixtures thereof toward copper and carbon-steel engine surfaces, such inhibition being important during fuel storage, fuel transport, and actual engine use.

It is also an additional object of this invention to provide an additive, which acts to promote more uniform spray patterns and assists in cleansing injectors in diesel engines.

Other aspects, objects and advantages of this invention will be evident to those skilled in the art in view of this disclosure.

The above and other objects of this invention are met by a fuel additive comprising an ether, a Group A metal salt of an organic acid, and a Group 118 metal salt of an organic acid. Additive combinations of barium and zinc salts of alkanoic acids branched in the alpha position, and glycol ethers, particularly alkyl ethers of ethylene glycol, impart particularly significant reduced smoke and soot forming properties to fuels. An especially effective additive is a mixture of the monomethyl ether of ethylene glycol and of bariumand zinc- Z-ethylhexanoates, wherein the weight ratio of barium to zinc metal is about l0 to l and the weight ratio of ether to carboxylates is from about 2:1 to l.5:l.

Fuel additives having further improved smoke suppressant characteristics are obtained when the aforesaid carboxylatesether mixtures also have incorporated therein a Group "A metal sulfonate, particularly a barium alkaryl sulfonate. A particularly preferred additive is a mixture of l-methoxy-2- propanol, a barium alkaryl sulfonate having a Molecular Weight of about 1000, barium 2-ethylhexanoate, and zinc-2- ethylhexanoate.

A fuel mixture having reduced soot and smoking characteristics is formed when the aforesaid carboxylates, ether and sulfonate mixtures are dispersed or dissolved in liquid hydrocarbon fuels. A preferred fuel mixture is a diesel fuel containing from about 0.2 to 0.5 percent by weight barium alkaryl sulfonate, from about 0.l to 0.6 percent by weight barium and zinc 2-ethylhexanoates and from about 0.2 to 0.5 percent by weight l-methoxy-Z-propanol.

Further, according to the invention there is provided a method for operating an internal combustion engine which comprises passing a liquid hydrocarbon fuel mixture containing an additive of this invention through the fuel supply system to the combustion chamber of said engine, and causing ignition of the fuel therein in normal fashion. This method of operation is particularly effective in operating a compression ignition engine utilizing the unique fuel additives.

In general, the Group HA and Group B metals may be combined with any organic acids to form the salts employed in this invention. Such salts can be aliphatic or aromatic carboxylates, e.g. alkyl, aryl, alkaryl, alkenyl, alkynyl, aralkyl or alicyclic. Some specific examples of acids are: methacrylic, ethanoic, propanoic, butanoic, Z-ethylhexanoic, decanoic, eicosanoic, tricontanoic, benzoic, naphthoic, 2-phenylethanoic, 3-propylbenzoic, cyclobutanoic, cyclodecanoic, glycolic, propynoic, fumaric, and the like. It is. to be understood that in each case the acid anion of Group "A metal salt may be identical to or different from the acid anion of the Group B metal salt. Further, a mixed (unsymmetric) salt ofa Group A and/or Group llB metal may be employed. The Group "A and/or Group B metal mixed (unsymmetrical) salts are employed, for example, together with symmetric salts or unsymmetric salts of similar or dissimilar Group llA and/or Group IIB metals.

Some specific salts which may be combined with ethers to form smoke suppressant mixtures include: barium and cadmium 2-ethylhexanoates; strontium decanoate and cadmium 3- methylnonanoate; barium and cadmium o-propylbenzoates; calcium and cadmium cyclobutanoates; magnesium methylcycloheptanoate and zinc 2-ethylpentanoate; strontium hexanoate and mercury Zethylbutanoate; strontium hexanoate and mercury 2-ethylbutanoate; beryllium and zinc oleates or linoleates; and barium fumarate and zinc octanoate. Some specific mixed salt combinations include: barium 2-ethylhexanoate 2,2-dimethylpropanoate and zinc Z-methyldecanoate; barium methacrylate pentanoate and cadmium glycolate tridecanoate.

The others employed in the present invention are, in general, those having the following structural formulas: R(O- R'-),,OR" wherein n is an integer preferably between about 0 to l0; R is a hydrocarbyl radical, R" is hydrogen or hydrocarbyl such that, when n is a whole integer, R is hydrogen or hydrocarbyl, and when n is zero, R" is hydrocarbyl, and R is a hydrocarbylene radical, such as methylene, ethylene or the like, and the total number of carbon atoms in a molecule is preferably less than about 30; and

wherein n is an integer preferably having the value of l or 2, and R and R are hydrocarbylene radicals and the molecule preferably contains less than about 30 carbon atoms.

Thus, when R and R are hydrocarbyl radicals, typical groups include, for instance: alkyl, alkenyl, aryl, alkaryl, aralkyl, or alicyclic radicals. Examples of suitable hydrocarbyl radicals are: methyl, ethyl, propyl, butyl, 2-ethylhexyl, neodecyl, dodecyl, octadecyl, eicosyl, nonacosyl, phenyl, naphthyl, benzyl, tolyl, ethylphenyl, phenylhexyl, propylphenyl cyclohexyl, cyclopropyl, cyclopentyl, butenyl, octenyl, linoleyl, etc.

When R and R are hydrocarbylene radicals, typical groups include, for example: alkylene, arylene, alkarylene, aralkylene, alkenylene or alicyclene radicals. Suitable hydrocarbylene radicals are: methylene, ethylene, propylene, isohexylene, decylene, phenylene, cyclohexylene, pentenylene, etc.

Examples of simple ethers useful in this invention are: diethyl ether, isopropyl ether, methyltert-butyl ether, ethylnbutyl ether, decyl butyl ether, nonacosyl methyl ether, allyl ethyl ether, vinyl isopropyl ether, cyclopropyl methyl ether, dicyclobutyl ether, methyl ethyl ether, benzyl methyl ether, benzyl ethyl ether, diphenyl ether, anisole, bis(2- chloroisopropyl) ether, and the like.

Examples of heterocyclic ethers useful in this invention are: such heterocyclic monoethers as tetrahydrofuran, ethylene oxide, propylene oxide, furan; such heterocyclic diethers as para-dioxane; meta-dioxane; dioxolane; 2-(3-heptyl) 1,3-dioxolane; 2-(3-heptyl) 1,3-dioxan-5-ol; 2-(3-heptyl) l,3-dioxolane-4-methanol; and such heterocyclic triethers as symtrioxane; ethyltrioxane; and the like.

DESCRIPTION OF PREFERRED EMBODIMENTS Enhanced reduction of smoke and soot from fuel combustion is obtained when barium and zinc salts of organic acids are employed.

Low Molecular Weight alkanoic acids, and especially alkanoic acids having from about four to 12 carbon atoms, are particularly preferred. The acids employed are preferably soluble in fuels.

Generally the alkanoic acyclic acids tend to leave fewer deposits on combustion and oxidize more readily than unsaturated or cyclic acids, and accordingly are preferred.

Further improvement in smoke suppression is obtained when the Group "A and Group 113 salts of organic acids, especially alkanoic acids having from four to 12 carbon atoms, and particularly the barium and zinc salts thereof, are branched in the alpha position.

Examples of suitable salts include those formed by combining any of the Group 11A and Group B metals with any of the acids set forth in the following table to form symmetrical or 2-Propylnonanoic acid 2-Methylundecanoic acid 2,2-Diethylheptanoic acid 2,2-Dimethyldecanoic acid An especially preferred salt additive is the combination of Group A and Group "B salts of 2-ethylhexanoic acid, and particularly, of barium and zinc 2-ethylhexanoates and of barium and cadmium 2-ethylhexanoates.

It is to be recognized that the di and poly carboxylic homologs of those monocarboxylates already described may be substituted therefor. Examples of such homologs include: barium and zinc adipates; strontium and zinc octadecanedioates; barium and cadmium pimelates; and the like.

Group IIA salts of carboxylic acids can be prepared for example, by reacting 2 moles carboxylic acid with 1 mole powdered dry Group llA metal hydroxide in hydrocarbon or petroleum solvent, and raising the temperature above C. to drive off the water formed. A composite of Group "A and Group "B salts of carboxylic acids can be prepared, for example, in one reaction step, by similarly reacting 2 moles of one or more carboxylic acids with (l-x) mole dry Group "A hydroxide and x mole dry Group "B hydroxide, where x is stoichiometrically calculated to supply a desired weight percent Group IIB metal in the product. The metal carboxylate products are usually solids, but are preferably used as a clear solution in a petroleum solvent. Solubility of salts in petroleum solvent can be increased by heating, addition of small quantity of oxygenated coordinating solubilizer, and/or use of ultrasonics.

Further, it will be recognized that derivatives of the aforementioned metal carboxylates having groups, preferably polar, substituted in place of hydrogen may also be incorporated into hydrocarbon fuels. Such substitutents must be essentially nonreactive to the fuel and include, for example, such polar groups as halogen, amino, nitro, nitrate, hydroxyl,

and the like.

Especially suitable ethers are the monoalkyl ethers of glycols and in particular, of ethylene glycol such as: monoethyl ether of ethylene glycol, monopentyl ether of ethylene glycol, mono(2-ethylbutyl) ether of ethylene glycol, monopropyl ether of ethylene glycol, and monopropyl ether of propylene glycol; and the diethers of glycols and, particularly, of ethylene glycol, such as dibutyl ether of ethylene glycol.

Ethers producing unusually good soot and smoke reduction in fuels in conjunction with the carboxylates of this invention are the monomethyl ether of ethylene glycol and l-methoxy- 2-propanol.

Additionally, fuel mixtures of dialkyl ethers of ethylene glycol, and particularly of dimethyl ether of ethylene glycol, commonly called glyme, exhibit improved Cetane Numbers, as compared to diesel fuels without said ethers, as well as effective soot and smoke reductions. This improvement is also seen in such dialkyl ethers of polyalkyleneoxy glycols as dimethyl ether of triethylene glycol. Accordingly, such ethers comprise another particularly preferredcla sgfethers.

It will be recognized that the derivatives of the aforementioned ethers having groups, preferably polar, substituted in place of hydrogen may also be incorporated into fuels. Such substituents must be essentially nonreactive to fuel and include such polar groups as halogen, amino, nitro, nitrate, hydroxyl, and the like.

Typical fuel additives of this invention employed in internal combustion engines include those formed by combining any calcium o-propylbenzenesulfonate; magnesium cyclooctanesulfonate;

Group lIA salt Group 1113 salt Ether Beryllium isobutanoatc Mercury 2-ethylpentan0ate Diethyl other.

Barium 2-ethyldecanoatenu Strontium linoleate Barium 3-methyltetradecanoate 2,3-diethylundecanoat Magnesium 2-phenylethanoate Calcium cyclopentanoate Preferred fuel additives of this invention include additives 1-6, the latter three being especially preferred,

1, Barium Z-methylpropanoate Zinc Z-methylpropanoate Mcnomethyl ether of propylene glycol 2. Barium Z-ethylbutanoate Zinc Z-ethyloctanoate Diethyl ether of pentylene glycol 3. Barium Z-methylundecanoate 2ethylpropanoate Zinc 2methylundecanoate Moncmethyl ether of triethylene glycol 4. Barium Z-ethylhexanoate Zinc Z-ethylhexanoate Monomethyl ether ofethylcne glycol 5. Barium Z-ethylhexanoate Zinc Lethylhexanoate Dimethyl ether of ethylene glycol 6. Barium 2ethylhexanoate Zinc Z-ethylhexanoate lMethoxy-2-propanol in a preferred embodiment of this invention, a Group llA metal sulfonate is incorporated in the aforesaid carboxylatesether additive mixes.

The sulfonic acids from which the sulfonates employed in the present invention are formed are those having the following structural formula:

R-SO .,H,

where R is a hydrocarbyl radical.

R may be an alkyl, alkenyl, aryl, alkaryl, alkynyl, aralkyl or alicyclic radical. Examples of suitable R groups are: methyl, propyl, 2-ethylhexyl, neodecyl, dodecyl, octadecyl, eicosyl, pentacosyl, phenyl, naphthyl, benzyl, tolyl, ethylphenyl, phenylhexyl, cyclohexyl, cyclopropyl, butenyl, linoleyl, propynyl, hexynyl, and the like.

Examples of sulfonic acids employed as sulfonates are: methanesulfonic acid, decanesulfonic acid, Z-ethylhexanesulfonic acid, pentanesulfonic acid, phenylmethanesulfonic acid, decylbenzenesulfonic acid, naphthalenesulfonic acid, octenesulfonic acid, cyclohexanesulfonic acid, and the like, and mixtures thereof. Further, mixed (unsymmetric) sulfonates Zinc 2,2-dimethyloctanoate Cadmium 2-hepteuoate Zinc ZAdibutyIbenZoate. Zinc 3-pheuyldecanoate Q-ethylnonanoate. Monoethyl ether of dccylcuc glycol. I Cadmium cyclobutanoatc B num 2-methylbenzoate Mercury Spropylbenzoate l.

Hexyl pentyl other. Dipropyl ether of propylene glycol. Methyl ethyl ether of ethylene glycol.

beryllium oleylsulfonate;

barium 2,Z-dimethylundecanesulfonate; barium hexanesulfonate p-toluenesulfonate; calcium naphthalene-l ,6-disulfonate;

and mixtures thereof.

Enhanced smoke suppressant characteristics are obtained when barium sulfonates are employed.

Generally it is preferred that fuel'soluble sulfonates be used, such as high Molecular Weight petroleum sulfonates, including "mahogany" acid sulfonates.

Naturally occuring alkaryl hydrocarbons, such as those found in mixed kerosene fraction of petroleum, may be employed as the hydrocarbyl substituents of the sulfonic acids. The sulfonic acids may be made according to the processes disclosed in US. Pat. No. 2,395,713 and US. Pat. No. 2,388,677 and refined according to U.S. Pat. No. 2,387,866.

Synthetically produced mixed alkaryl sulfonates of Group A metals, especially barium having two alkyl groups per aromatic group are well suited. It is particularly preferred that each alkyl group of the mixed sulfonates is a linear group of from about 14 to 18 carbon atoms, said sulfonate having a Molecular Weight of from 800 to 1,500, preferably from 900 to 1,100.

Examples of preferred sulfonates include: barium 2-hexadecyl-3-heptadecylbenzesulfonate;

barium 2-(B-methylpentadecyl)-6-octadecylbenzenesulfonate;

barium 2-octadecyl-8-(2-ethylhexadecyl) naphthalenesulfonate;

barium 2-ethyltetradecyl-8-(3-methyitetradecyl) naphthalenesulfonate;

may be employed to raise or lower the metal content, as l desired. Typical additive mixtures of this embodiment of the inven- Some specific sulfonates useful in this invention include: tion employed in fuels include those formed by combining any barium nonanesulfonate; Group llA carboxylate, any Group llB carboxylate, any ether strontium Z-ethylheptanesulfonate; and any Group "A sulfonate set forth below.

Group IIA salt Group IIB salt Ether Group HA sullonatu Beryllium YIP ODanOatB Mercury ZethyIpentanoatQUU Diethy] other; Barium tridccanvsulionatc. a um hthyld canoate Zinc 2,2-dimethyloctanoate. Hcxylpentyl other Strontium hcxudecylbcnzuncsulfollut Strontium hnoleate undecanoate. Cadrnlum 2-hepteuoate Dipropyl other of propylene glycol. Calcium cyclohtxuncsulfonatc. Magnesium phcnylcthanoate Zinc 2:phenyldccan0ate Mouoethyl ether of decylene glycol". Magnesium (lCCtlWStlilOllflLO. c-algum Cyclopentanoate- Cadmium cyclobutanoate. Dibenzyl cthor Beryllium nap]:thy]propancsullonnto. Bani-1 2-I cthy1benzoate..... Mercury 2-propy1benzoato, Beuzyl ethyl (ZLh[I Barium r1onadvcanosullonatv- Mouophenyl ether of at n one glycol Preferred mixtures of the invention containing sulfonates includes additives 1-6, the latter three being especially preferred.

1. Barium Z-methylpropanoate Zinc 2-methylpropanoate Monomethyl ether of propylene glycol 2. Barium Z-cthylbutlnoate Zinc Z-ethyloctoate Diethyl ether of pentylene glycol Barium l,2,3-tridodecylnaphthalenesulfonate 3. Barium 2-methylundecnnoate Zinc 2-methylundecunoate Monomethyl ether of triethylene glycol Barium 2-octadecy|anthracenesulfonate 4. Barium 2-ethylhexanoate Zinc 2-ethylhexanonte Monomethyl ether of ethylene glycol Barium 2-undecyl-3-dodecy1benzenesulfonate 5. Barium Z-ethylhexanoate Zinc Z-ethylhexanoate Dimethyl ether ofethylene glycol Barium Z-heptadecyl-8-decylnapthalenesulfonate 6. Barium Z-ethylhexanoate Zinc Z-ethylhexanoate Dimethyl ether cfdiethylene glycol Barium 2-tridecyl-4-pentadecylbenzenesulfonate Generally, the weight proportions of ether to carboxylates in the additives of this invention may vary between wide limits. It is preferred that the weight ratio of ether to the total combined weight of Group HA and Group IIB carboxylates is between about four parts to 1.0 parts ether per part carboxylates. In the case of the barium and zinc alkanoates and glycol ether additive mixtures, the weight ratio of ether to the combined weight of barium and zinc alkanoates is preferably between about three to 1.5 parts ether per part carboxylates.

In the case of the especially preferred additive mixtures of barium and zinc 2-ethylhexanoates, and monomethyl ether of ethylene glycol, it has been found that best results are obtained when the weight ratio of ether to the total weight of barium and zinc carboxylates is from about 2.0 to 1.5 parts ether per part carboxylates.

A synergistic effect resulting in improved smoke and soot reduction is observed when the proportion of Group IIA metal carboxylate is greater than the proportion of Group IIB metal carboxylate. This effect is especially evident where the Group IIA carboxylate is a barium salt and the Group IIB carboxylate is a zinc salt. Further reductions are noticed when the ratio of Group IIA metal to Group 118 metal (in the carboxylates) and especially of barium metal to zinc is from about 5:1 to 30:1 and particularly, from about 8:1 to 12:1 by weight. For best results it is especially preferred that the weight ratio be about parts barium per part zinc.

A synergistic effect is also seen between the ether and the aforementioned carboxylate mixtures. This effect is particularly evident when alkyl glycol ethers, particularly the mono and dialkyl ethers of ethylene glycol, and especially the monomethyl ether of ethylene glycol, are employed.

Generally the sulfonates are employed in the carboxylates and ether additives of this invention to provide additional smoke suppressant improvement in the aforesaid salts and ether mixtures and to enhance the beneficial features of the additives, such as the detergency effects, and the anticorrosion effects.

For these and other purposes, generally the weight proportion of carboxylates and ether to sulfonates in the additives is from about one to three parts carboxylates and from about one to two parts ether per one to two parts sulfonate, and preferably from about one to two parts ether and one to two parts sulfonate per part total carboxylates.

In the case of the especially preferred additive of barium and zinc 2-ethylhexanoates, l-methoxy-Z-propanol and the barium alkaryl sulfonate having a Molecular Weight of about 1000, it has been found that best results are obtained when the weight ratio of additive components is about 1.4 parts ether and 1.4 parts sulfonate per part barium and zinc carboxylates.

Generally, the additive mixtures are employed in amounts which produce a significant reduction in the smoke and soot characteristics of hydrocarbon fuel. For this purpose, generally at least about 0.05 percent by weight of additive mixture should be utilized. Although amounts in excess of about 5 percent by weight may be employed, practical smoke and soot reductions are usually achieved with lesser amounts.

Usually, enhanced smoke reductions are achieved when the total concentration of Group IIA metal present as a carboxylate salt and, if present, as a sulfonate, in the fuel mixture is from 0.04 to 0.08 percent by weight, preferably about 0.07 percent by weight.

Generally, the mixtures of Group IIA and Group 118 salts of this invention are employed in amounts which produce effective smoke and soot suppression. For this purpose, a minor amount of salts, usually a total of at least 0.05 percent by weight should be employed. Although greater amounts may be employed, generally it is not necessary to use more than about 5 percent by weight.

For best results it is preferred that the salts be employed in a total concentration of about from 0.1 to 2 percent by weight.

In the case of the especially preferred diesel fuel mixture of barium-and-zinc-2-ethylhexanoates it has been found that best results are obtained when a total of from about 0.1 to 0.6 percent by weight of salts are employed.

Basically the ethers are employed in amounts necessary to produce a significant reduction in the smoke and soot characteristics of the fuel mixture. For this purpose, generally at least 0.05 percent by weight of ether should be utilized. Although amounts in excess of about 5 percent by weight may be employed, practical smoke and soot reductions are usually achieved with lesser amounts. Best results are attained when the ethers are employed in concentration from about 0.1 to 1 percent by weight.

In the case of the particularly preferred diesel fuel mixtures of barium-and-zinc-2-ethylhexanoates and glycol ethers, it has been found that best results are obtained when from about 0.2 to 0.5 percent by weight of ether is employed, and from about 0.1 to 0.6 percent by weight of salts are employed.

The weight percentages of additives are based upon the weight of additive as compared to the total weight of the fuel mixture.

In order to reduce the amount of visible black soot and smoke emitted from internal combustion engines significantly, the Group IIA metal sulfonates are employed in minor amounts, at least at about 0.05 percent by weight. Generally no more than about 1 percent by weight of sulfonate based on the total weight of the fuel mixture, is employed. If greater amounts are employed no further substantial visible smoke and soot reductions are obtained.

For best results it is preferred that the Group "A metal sulfonates, be employed in amounts from about 0.1 to- 0.8 percent by weight based on the total weight of the fuel mixture.

In the case of the especially preferred diesel fuel mixtures of barium and zinc alkanoates and glycol ethers, best results are obtained when the sulfonates, especially barium alkaryl sulfonates, are employed in amounts from about 0.2 to 0.5 percent by weight, based on the total weight of the fuel mixture.

Generally, to form the novel carboxylates-ether mixtures the alkanoates are admixed with the ether by conventional .means. If need be, a solubilizer may be added to the novel additive mixtures in amounts sufficient to form a homogeneous liquid concentrate with enhanced solubility in liquid hydrocarbon fuels.

To prepare fuel mixtures of the carboxylates, ether, and sulfonate additive mixes advantageously, one may initially dissolve or disperse the metal carboxylates in the fuel, then add the ether to the carboxylate-fuel mixture, and finally add the sulfonate to the fuel mixture. The additive mix may also be added directly to the fuel, or a solubilizer may be added to the additive mix and the resulting composition admixed with a fuel.

Generally, the aforesaid solubilizers are inert petroleum solvents, such as petroleum ether, a hydrocarbon fuel, Varsol, White Oil, alcohols, especially glycols, and the like, and mixtures thereof.

If a solubilizer is employed in the case of the salts, ether and sulfonate additives, it is preferred that the proportion of salts be between about to 30 percent by weight, the ethers between to 40 percent by weight, the sulfonates between 15 to 25 percent by weight, and the solvent between about 60 to 5 percent by weight, wherein said weight percentages are based upon the total weight of said salts, ether, sulfonate, and solvent.

In general, any liquid hydrocarbon fuel including heating fuels, and particularly those fuels useful in internal combustion engines can be employed as the fuel to which the novel additives may be added. It is preferred that the liquid hydrocarbon fuel be a diesel fuel having an initial boiling point of about 300 F. and an end distillation point of about 750 F. Diesel fuels having a boiling range of from about 400 F. to about 675 P. such as No.. 2 diesel fuel are especially preferred.

The following examples are given to further illustrate the nature of the invention and are not limitative of scope.

EXAMPLE I In order to demonstrate the smoke and soot suppressancy of the additives of this invention in hydrocarbon fuels, a diesel fuel mixture was prepared as follows: about 60 parts by weight of a liquid solution containing about 19 parts by weight barium 2-ethylhexanoate, about 3 parts by weight zinc 2-ethylhexanoate and about 38 parts inert petroleum solvent was admixed with about 40 parts of a designated glycol ether. The ratio of ether to salts was about 1.8 to 1. Selected quantities of nected to a two-way valve of the smoke meter. Typical engine temperatures were:

Intake Air I50 F. Gallery Oil l20-l40" F. Coolant 212 F.

Firstly, the engine was warmed up on the base fuel at a condition wherein no visible black smoke was observed in the exhaust gases. The fuel flow was increased until the fuel flow was about 13 cubic centimeters per minute, corresponding to the appearance of visible black smoke in the exhaust gases and a Hartridge Smoke Number (HSN) reading ofabout 40.

The smoke suppressant fuel mixture of the invention was then substituted for the base fuel and the engine was run for about 5 minutes to allow stabilization. The smoke meter reading was then recorded. Next a mixture of a base fuel and 0.7 percent by weight of commercially available smoke suppressant was substituted in place of the additive mixture as a reference. After a 5-minute delay for engine stabilization, Smoke Meter readings were recorded. The cycle of base fuel, additive fuel, and reference fuel was repeated two additional times.

The following table illustrates the effectiveness of the novel additive mixtures, In the table, the lllartridge Smoke Number (HSN) values are given as the average of the three consecurive uns-.1" ffPsteatt Eff ti e i repre ented by the equation [HSN HSN additive] Hemmar HSN reference] X 100% and is a measure of the efficiency of the novel fuel mixtures, as compared to a commercial smoke suppressant fuel mixture. The weight percent of additive is based on the weight of the component as compared to the total weight of the fuel mixture.

RESULT OF SMOKE SUPPRESSAN 'I TESTS Weight llSN, lercnnt percent of HSN. additive IISN, (floc- Additive in base fuel additive base fuel in base fut-l reference tivonoss Barium Z-ethylhexanoate O. 13 Zinc Zethylhexanoate 0. 01 d2 5 5 I00 Monomethyl ether of ethylene glycol 0 26 Total 0.

Barium 2-ethylhexanoate 0. 34 Zinc Z-ethylhexanoate 0. 03 38 8 'J 103 Monomethyl ether of ethylene glycol 0.

Total 0 87 Barium Z-ethylhexanoate 0. 23 37 (1 38 o. 4: N Zinc Z-ethylhexanoate 0. 39 67 65 10 d Monomethyl ether of ethylene glycol 0. 50 4'2 38 a 12 1. Cctane Number. minimum 43 2. Flashpoinl, F. minimum 140 3. Distillation, 90 percent recovered, F. maximum 600 4. Viscosity, ccntistokes at l00 F. 2.l4.3 5. Carbon residue IOpercent bottoms) 0.25

The Smoke suppressants were evaluated in a single cylinder cetane type diesel engine equipped with a Hartridge Smoke Meter. An exhaust probe was inserted in the exhaust pipe about 4 feet from the exhaust manifold. The probe was con- The value of lOO on the Hartridge Smoke Number Scale represents completely black smoke, 30 and below represents a clear exhaust acceptable under all running conditions. Use of zinc 2-ethylhexanoate as the only additive, at concentrations from 0 to 0.39 weight percent in base fuel, gave zero percent effectiveness in smoke reduction.

The results set forth in the preceding example demonstrate the effectiveness of fuels containing barium and zinc 2-ethylhexanoates, and glycol ethers in reducing smoke and soot formation. The results also demonstrate the synergistic interaction between the barium and zinc salts which is especially evident when the ratio of barium to zinc metal is about 10 to 1. Similar results are obtained when other combinations of Group 11A and Group IIB metal salts are substituted for the barium and zinc salts in the above example.

Thus when the salts formed by the combination of Group lIA metals, Group 118 metals and the acids listed below are substituted for the barium and zinc Z-ethylhexanoate employed in example I satisfactory results are obtained.

Group "A Group "B Acids Strontium Zinc Octanoic acid Calcium Cadmium Cyclopentanoic acid Magnesium Mercury Z-Propylbenzoic acid Beryllium 2-Propylhexanoic acid Barium 2,2-Dimethyloctanoic acid The results of the preceding example also demonstrate the effectiveness of fuel mixtures of alkyl ethers of ethylene glycol, and especially the monomethyl ether of ethylene glycol and of barium and zinc salts of low Molecular Weight alkanoic acids, particularly those acids branched in the alpha position, in reducing smoke and soot. Similar results are also obtained when other combinations of ethers and Group HA and Group .Smoke Meter readings were noted. Next the fuel throttle was opened slightly to give about 150 BHP and thereafter to give about 155 BHP. At both these loads, smoke meter readings were noted.

Next, a smoke suppressant fuel mixture of the invention was substituted for the base fuel and smoke meter readings were taken at the three engine power levels previously employed.

The following table illustrates the effectiveness of the novel additive mixtures.

RESULTS OF SMOKE SUPPRESSANT TESTS Weight H SN Percent percent of Brake-horse HSN. base additive reduction Additive in base fuel additive power fuel in base fuel in smoke No. 1:

Barium 2-ethy1hexanoate 0. 13 140 26 17 35 Zinc 2-ethy1hexanoate 0. 01 150 37 22 4O 1-methoxy-2-propanol 0. 26 155 52 31 40 Total 0.40

Barium 2-ethylhexanoate O. 064 140 25 17 Zinc 2-ethylhexanoate. 0.006 150 37 32 14 l-Methoxy-2-pr0panoL 0. 130 155 50 43 14 Total 0. 200

The reduction in smoke is represented by:

EXAMPLE III 118 metal salts of organic acids are substituted for the salts and ethers in the above example. Satisfactory results are obtained when other ethers such as methyl ethyl ether, diethyl ether of diethy lene glycol, dioxane, and dibenzyl ether are substituted for the monomethyl ether of ethylene glycol.

It should be noted that the components of the fuel mixtures of this example, when tested individually in diesel fuel, showed much less effectiveness in reducing soot and smoke than the combination thereof. This demonstrates that multiple synergism is obtained when the metal salt-fuel mixtures have ethers additionally incorporated.

When other liquid hydrocarbon fuels, such as jet fuel, heating fuel, gasoline, etc., are substituted for the diesel fuel tested, the smoke and soot forming properties of these fuels are beneficially improved.

EXAMPLE II In order to further demonstrate the smoke and soot suppressancy of hydrocarbon fuel mixtures of the additives of this invention, a diesel fuel mixture was prepared according to the procedure followed in example I. Selected quantities of a concentrate, having the same proportions of carboxylates and In order to evaluate the smoke suppressant effectiveness of the carboxylates, ether and sulfonate additive mixtures of this invention, selected quantities of barium and zinc 2-ethylhexanoate, the monomethyl ether of ethylene glycol and a synthetic barium alkaryl sulfonate (14.6 percent Ba metal) with a Molecular Weight of about 1000 were individually dissolved in the No. 2 diesel fuel of example I to form a fuel mixture. The fuel mixture was tested by the same procedure as described in example I. The mixture had a weight ratio of additive components of about 1.4 parts ether to 1.4 parts sulfonate per part carboxylates. The weight ratio of the barium carboxylate to the zinc carboxylate was about 10 to l. The barium and zinc carboxylates component of the additive was added to the fuel as a liquid, the composition of the liquid being about 37 parts by weight carboxylates to 63 parts by weight inert petroleum solvent. The reference standard of example I was also tested for comparing soot and smoke reductions.

The following table illustrates the effectiveness of this aspect of the invention.

RESULTS OF SMOKE SUPPRESSANT TESTS Test results HSN, Weight HSN, base additive HSN, Percent Component in base fuel percent fuel in base fuel reference efiectiveness No. 1:

Barium 2-ethylhexanoate 0. 11 Zinc Z-ethylhexanoate 0.01 33 5 5 Monomethyl ether of ethylene glycol. 0. 17 Barium dialkarylsulfonate 0.17

Total 0 46 Barium 2-ethylhexanoate 0. 16 Zine 2ethylhexanoate 0.02 66 7 7 7 Mon Jmethyl ether of ethylene glycol. 0. 25 Barium dialkarylsulfonate 0.25

Total 0. 68

Barium 2-ethylhexanoate 0 16 Zinc Z-ethylhexanoate 0 O2 53 21 11 I5 Monomethyl ether of ethylene glycol 0 50 Total 0.68

The results of the preceding example demonstrate the effectiveness of the carboxylates, ether and sulfonate additive mixtures, particularly of the barium and zinc alkanoates, glycol ethers, and barium alkaryl sulfonates, as smoke and soot supble of simulating the inertia produced by the motion of the truck tractor under actual driving conditions.

In order to measure the smoke and soot produced during operation of the engines, a light extinction full-flow smokemepressants for fuels. Similar results are obtained when other ter employed by the United States Public Health Service was combinations of Group HA and Group IIB metal salts of ormounted directly on the exhaust stack of the truck tractor. ganic acids, ethers, and Group IIA metal sulfonates are sub- The smokemeter was mounted 5.5 inches above the exhaust stituted for the components in the above example. pipe so that a light source mounted at one end of a collimating The smoke and soot reductions achieved in fuels by employtube would project a beam of light directly through the exing salts, ether, and sulfonate additives are demonstrated by haust plume. A photoelectric collector cell mounted on the comparing the unexpectedly increased effectiveness of addiother end of the collimating tube measured the light passing tive 02, as contrasted to additive 03, in this example, wherein through he xh t pl m, n he p r n transmittance was a portion of the ether of additive 03 was replaced by a Group then recorded. Generally, a rating of 20 percent opacity (or IlA metal sulfonate. light obscuration) corresponds to a Ringlemann Number of 1.

The Cummins HN-220 engine and tractor were operated at EXAMPLE IV simulated constant speed conditions corresponding to the fol- To further illustrate the novel carboxylates, ether and sul- Owmg engmg Speed and vehlcle Speedsfonate smoke and soot suppressant additive mixes of this inr d vention, mixtures having the same components and proporopml'ng w l? pee tions of batch #1 in example III, with the exception that lmethoxy-2-propanol was substituted for the monomethyl 3 Egg :8 ether of ethylene glycol, were prepared and selected quanti- C 1900 32 ties were added to the No. 2 fuel described below. D 2100 35 The No. 2 diesel fuel possessed the following characteristics:

In order to evaluate the effect of the smoke suppressant adhcmne Number ditives during operation of the truck trailers, the following 2. Distillation, 10 percent point, F 4|4 p dure was employed. I l

90 percent point. F. 562 The smokemeter was zeroed in w1th air to simulate a no- 3, Totalsulsur 0 0-072 smoke" condition. The engine was started and accelerated to 2 3'2" Am seventh gear and operated at Operating Condition A. After 30 Aromatics, 25 seconds, the smokemeter reading was taken. Then the speed olefinstk 0 was increased to that specified in Operating Condition B and 35 after 30 seconds, the smokemeter reading was taken. This Th e smoke Suppressams were evalufted under Slmulated procedure was followed for Operating Conditions C and D. conditions of constant speed in a Cummins Nil-220, naturally The entire cycle was repeated two additional times and the aspirated, six cylinder four cycle engine mounted in a 1965 Inresults reported represent an average f three runs ternational Harvester DC OF-405 cab-over tandem-drive axle Th reduction i Smoke i represented b truck tractor. 4O

To simulate actual driving conditions the tractor was p ybuse ruei p yaaattivel X mounted on a modified Clayton Chassis dynamometer, capap ybuse fuel Additive Smoke tests at constant speed Percent opacity, Percent additive Percent Weight Operating opacity, in base smoke Component in base fuel percent condition base fuel fuel reduction N0. 1:

Barium 2ethylhexanoate 013 A 24 14 4 Zinc 2-ethylhexanoate 0 01 B 25 13 48 Monomethyl ether of ethylene glycol O. 26 C 28 16 43 Total v. 0. 40

Barium Z-ethylhexanoate 0. 064 A 2*} lj Zinc Z-ethylhexauoate 0.006 B 20 14 g Monomethyl ether of ethylene glycol 0 C I) 28,30 0, 22

Total 0.200

Barium 2-ethylhexanoate 0.11 A 24 1 58 Zinc 2-ethylhexanoate 001 B 25 12 E9 l-methoxy-2-propanol.i. 0.17 C 28 1- Barium alkztrylsulfonate .1 0 17 D 30 13 a Total 0.46

Nov 4:

Barium 2-ethylhexanoate- 0.055 A 24 13 Zine 2-ethylhexanoate 0.005 B 25 14 43 1-rnethoxy-2-propanol 0. 08 C 28 16 40 Barium alkarylsulfona 0.089 I) 30 18 Total 0 230 Barium Z-ethylhexanoate 0.14 A Z Zine 2-ethylhexanoate 0. 01 B 9 4 82 l-methoxy-2-propanol 0.22 C 5 78 Barium alkarylsulfonate H 0.22 D 3 Total 0 5d Barium 2ethylhexanoate 0.27 A g Zinc 2-ethylhexanoate 0.03 B 4 77 l-methoxy-2-propanol 0.44 C 2 6 7 Barium alkaiyl sulfonate 0. 44 D Total Operating Condition" refers to the previous table showing vehicle simulated speed, and r.p.m.

For the light extinction smokemeter a reading of one hundred percent opacity equals total absorption of light and zero percent opacity equals 100 percent light transmittance.

In the diesel fuel mixtures illustrated, the concentration of Group IIA metal was about from 0.04 to 0.15 percent by weight and the concentration of the zinc metal was from 0.002 to 0.009 percent by weight of the fuel mixture.

Best smoke suppressancy was obtained when the barium concentration in the fuel was about 0.07 percent by weight.

The results of this example further demonstrate the effectiveness of the smoke and soot suppressant additives of this invention. Similar results are expected when the additives are employed in other hydrocarbon fuels as gasoline, jet fuel, and heating fuels.

EXAMPLE V In order to test the tolerance of the novel fuel additive mixtures of this invention to water, selected quantities of the additives appearing in the table below were dissolved in 100 milliliters of the No. 2 diesel fuel, previously described in example I, and milliliters of water were added. The diesel fuel mixtures were at room temperature when tested. The water and diesel fuel additive mixtures were shaken vigorously and allowed to settle. The mixtures were observed at periodic intervals for 10 days. The results of the test after minutes are described in the table below.

Upon standing for 10 days, no haze was observed in the oil phases.

EXAMPLE V] In order to determine the effect of the new additives on the Cetane Number of diesel fuel, fuel mixture consisting of the No. 2 diesel fuel of example I in admixture with the additives of example V were tested against the No. 2 diesel fuel oil of example I. The Cetane Number of the No. 2 diesel fuel and novel fuel mixtures was determined by operating a single cylinder Cetane Test Engine in accordance with ASTM procedure 12-613. The Cetane Number of the No. 2 base diesel fuel was about 43 while the Cetane Numbers of base fuel containing the aforementioned additives were also about 43. The results demonstrate that fuel mixtures of the novel additives do not adversely effect Cetane Number of the base fuel.

EXAMPLE VIII jected to the DuPont 300 F. Accelerated Fuel Oil Stability Test.

Clear Fifty ml. of the diesel fuel mixtures were each aged in an oil bath held at 300 F. for minutes. The samples were then filtered under vacuum (16"Hg) through a 4.25 cm. No. I Whatman Paper held in Millipore filter holder. The test tubes that held the aged samples were rinsed with 3 ml. portions of nheptane; each wash being transferred to the filter holder. The filter holder and papers were washed with n-heptane under vacuum until free of fuel oil. The filters were air dried under vacuum and compared with reference standards. A fuel hav' ing a matching standard of No. 7 or lower is passing." The results of the test showed that the base fuel had a Pad Rating of 7, while the base fuel-additive mixtures each had a rating of 3.

EXAMPLE VIII In order to demonstrate the corrosion inhibition characteristics toward copper, which the smoke suppressant additives impart to fuels, particularly diesel fuel, the additives of example V were admixed with the diesel fuel of example I and tested according to ASTM procedure D-l30. The ratings of the individual additive fuel mixture and base fuel were 1A.

EXAMPLE IX To demonstrate the anticorrode effect of fuel mixtures containing the smoke suppressant additives of the invention on carbon steel under highly corrosive conditions, two-2-millimeter thick strips of carbon steel were separately immersed in the mixtures of the additives of example I in 400 milliliters (ml.) diesel fuel and 10 ml. ofa 4 percent sodium chloride solution at a temperature of l00 F. The mixtures were stirred at I000 r.p.m. and measurements were made at time intervals of the changes in voltage drop between the strips. Percent Corrosion was obtained from these measurements by means of previously obtained correlation between voltage drop versus Percent Corrosion measured for a carbon steel coupon tested under pipe line conditions. The following table describes the results of the test as noted after 24 hours immersion.

k Corrosion of Carbon Steel After 24 Hours The results show the enhanced anticorrode properties of fuel mixtures of the smoke suppressants of the invention. The additives were present in the diesel fuel in a concentration of about 0.007 weight percent.

EXAMPLE X To show the surfactant properties supplied to fuels by the smoke suppressants of this invention the additive-containing fuel blends of example V were tested in accordance with ASTM procedure D-97l to determine interfacial tension. Generally, the lower the tension, the greater is the surfactant property of the fuel. The table below illustrates the decrease in interfacial tension at 25 C., of diesel fuel mixtures versus distilled water.

lnterfaeial Tension. dyne/cm.

If desired, the fuel compositions of this invention may additionally contain oxidation inhibitors, corrosion inhibitors, antifoam agents, other smoke suppressants, sludge inhibitors, color stabilizers, and other additional agents adapted to improve the fuels in one or more respects. Further, other detergents, such as metal salts of monoesters of sulfuric acid formed from n-aliphatic alcohols containing from eight to 18 carbons, metal salts of di(2-ethyl-hexyl) sulfosuccinic acid, and especially Group llA salts, particularly barium salts, and mixtures thereof may be additionally incorporated to the additives.

lt will be understood that the specific embodiments set forth hereinabove are illustrative only and that the invention is not to be limited except as set forth in the following claims.

Therefore, 1 claim:

1. A smoke suppressant composition suitable for use in liquid hydrocarbon fuels comprising a Group HA and Group 118 metal salt of an alkanoic acid branched in the alpha position, a Group llB metal salt of an alkanoic acid branched in the alpha position, a group IIB metal salt of an alkanoic acid branched in the alpha position, an alkyl ether ofa glycol having about three to 10 carbon atoms and a Group "A metal sulfonate, wherein the weight ratio ofGroup llA metal to Group 118 metal in the alkanoates is from about to l to about 30 to 1 and the weight proportions of total alkanoates and ether to sulfonate is about 1 to 3 parts of total alkanoates and about 1 to 2 parts of ether to l to 2 parts of sulfonate.

2. The composition of claim 1 wherein the Group "A metal salt is a barium salt, the Group IIB metal salt is a zinc salt, and the Group A metal sulfonate is a barium hydrocarbyl sulfonate.

3. The composition of claim 2 wherein the weight ratio of barium to zinc in the alkanoates is from about 8:1 to 12:1.

4. The composition of claim 3 wherein the alkanoates each have from about four to 12 carbon atoms, and the sulfonate is a barium alkaryl sulfonate.

5. The composition of claim 3 wherein the Group llA metal salt is barium 2-ethylhexanoate, the Group "B metal salt is zinc Zethylhexanoate, the ether is l-methoxy-Z-propanol, the sulfonate is a barium alkaryl sulfonate having a Molecular Weight of from about 900 to l 100, the weight ratio of barium to zinc in the 2-ethylhexanoates is about to l, and the weight ratio of the ether, sulfonate and carboxylates is from about 1 to 2 parts ether and 1 to 2 parts sulfonate per part total carboxylates.

6. The composition of claim 5 wherein the monomethyl ether of ethylene glycol is substituted for l-methoxy-Z- propanol.

7. A liquid fuel composition having reduced smoking characteristics comprising a major proportion of a liquid hydrocarbon fuel and a minor proportion of a Group IIA metal salt of an alkanoic acid branched in the alpha position, a Group 1113 metal salt of an alkanoic acid branched in the alpha position, an alkyl ether of a glycol having about three to 10 carbon atoms and a Group IlA metal sulfonate, wherein the weight ratio of Group A metal to Group llB metal in the alkanoates is from about 5 to l to about 30 to 1 and the weight proportions of total alkanoates and ether to sulfonate is about 1 to 3 parts of total alkanoates and about 1 to 2 parts of ether to l to 2 parts of sulfonate.

8. The composition of claim 7 wherein the fuel is a diesel fuel, the total weight of Group HA and Group 118 metal salts of alkanoic acid is from about 0.05 to 5 percent by weight, the ether is present in amounts from about 0.05 to 5 percent by weight, the metal sulfonate is present in amounts from about 0.05 to 1 percent by weight, and wherein the weight percentages are based upon the total weight of the diesel fuel mixture.

9. The composition of claim 8 wherein the Group llA metal alkanoic acid salt is a barium salt, the Group IIB metal alkanoic acid salt is a zinc salt, and the Group llA metal sulfonate is a barium hydrocarbyl sulfonate.

110. The composition of claim 9 wherein the alkanoates each have from about four to 12 carbon atoms, and the sulfonate is a barium alkaryl sulfonate.

11. The composition of claim 10 wherein the total weight of barium and zinc alkanoates is from about 0.1 to 0.6 percent by weight, the glycol ether is present in amounts from about 0.2 to 0.5 percent by weight, the sulfonate is present in amounts from about 0.2 to 0.5 percent by weight, and the weight ratio of barium to zinc in the alkanoates is from about 8:1 to 12:1.

12. The composition of claim 11 wherein the Group IIA metal alkanoate is barium Z-ethylhexanoate, the Group IIB metal alkanoate is zinc Z-ethylhexanoate, the ether is 1- methoxy2-propanol, the sulfonate :is a barium alkaryl sulfonate having a Molecular Weight of from about 900 to 1100, and the weight ratio of barium to zinc in the Z-ethylhexanoates is about 10:1.

13. In the method of operating an internal combustion engine wherein a liquid hydrocarbon fuel is passed through a fuel supply system into a combustion chamber of said engine and said fuel is caused to ignite therein, the improvement comprising operating said engine on a hydrocarbon fuel containing a minor proportion of a Group lIA metal salt of an alkanoic acid branched in the alpha position, a Group IIB metal salt of an alkanoic acid branched in the alpha position, an alkyl ether ofa glycol having about 3 to 10 carbon atoms and a Group llA metal sulfonate, wherein the weight ratio of Group "A metal to Group IlB metal in the alkanoates is from about 5 to l to about 30 to l and the weight proportions of total alkanoates and ether to sulfonate is about 1 to 3 parts of total alkanoates and about 1 to 2 parts of ether to l to 2 parts of sulfonate.

114. In the method of operating a compression ignition engine wherein a diesel fuel is passed through a fuel supply system into a combustion chamber of said engine and said fuel is caused to ignite therein, the improvement comprising operating said engine on a diesel fuel containing a barium and a zinc alkanoate, wherein each alkanoate is branched in the alpha position, an alkyl ether ofa glycol having about three to 10 carbon atoms and a barium hydrocarbyl sulfonate wherein the total weight of said alkanoates are from about 0.05 to 5 percent by weight, said ether is present in amounts from about 0.05 to 5 percent by weight, and said sulfonate is present in amounts from 0.05 to 1 percent by weight, and the weight percentages are based on the total weight of fuel mixture.

15. The method of claim 14 wherein said fuel mixture is a diesel fuel containing barium 2-ethylhexanoate, zinc 2-ethylhexanoate, l-methoxy-Z-propanol, and a barium alkaryl sulfonate having a Molecular Weight of about 1000, wherein the weight ratio of barium to zinc in the Z-ethylhexanoates is about 10:1, the total weight of the alkanoates is from about 0.1 to 0.6 percent by weight, said ether is present in amounts from about 0.2 to 0.5 percent by weight, and said sulfonate 15 present in amounts from about 0.2 to 0.5 percent by weight, based on the total weight of diesel fuel mixture. 

2. The composition of claim 1 wherein the Group IIA metal salt is a barium salt, the Group IIB metal salt is a zinc salt, and the Group IIA metal sulfonate is a barium hydrocarbyl sulfonate.
 3. The composition of claim 2 wherein the weight ratio of barium to zinc in the alkanoates is from about 8:1 to 12:1.
 4. The composition of claim 3 wherein the alkanoates each have from about four to 12 carbon atoms, and the sulfonate is a barium alkaryl sulfonate.
 5. The composition of claim 3 wherein the Group IIA metal salt is barium 2-ethylhexanoate, the Group IIB metal salt is zinc 2ethylhexanoate, the ether is 1-methoxy-2-propanol, the sulfonate is a barium alkaryl sulfonate having a Molecular Weight of from about 900 to 1100, the weight ratio of barium to zinc in the 2-ethylhexanoates is about 10 to 1, and the weight ratio of the ether, sulfonate and carboxylates is from about 1 to 2 parts ether and 1 to 2 parts sulfonate per part total carboxylates.
 6. The composition of claim 5 wherein the monomethyl ether of ethylene glycol is substituted for 1-methoxy-2-propanol.
 7. A liquid fuel composition having reduced smoking characteristics comprising a major proportion of a liquid hydrocarbon fuel and a minor proportion of a Group IIA metal salt of an alkanoic acid branched in the alpha position, a Group IIB metal salt of an alkanoic acid branched in the alpha position, an alkyl ether of a glycol having about three to 10 carbon atoms and a Group IIA metal sulfonate, wherein the weight ratio of Group IIA metal to Group IIB metal in the alkanoates is from about 5 to 1 to about 30 to 1 and the weight proportions of total alkanoates and ether to sulfonate is about 1 to 3 parts of total alkanoates and about 1 to 2 parts of ether to 1 to 2 parts of sulfonate.
 8. The composition of claim 7 wherein the fuel is a diesel fuel, the total weight of Group IIA and Group IIB metal salts of alkanoic acid is from about 0.05 to 5 percent by weight, the ether is present in amounts from about 0.05 to 5 percent by weight, the metal sulfonate is present in amounts from about 0.05 to 1 percent by weight, and wherein the weight percentages are based upon the total weight of the diesel fuel mixture.
 9. The composition of claim 8 wherein the Group IIA metal alkanoic acid salt is a barium salt, the Group IIB metal alkanoic acid salt is a zinc salt, and the Group IIA metal sulfonate is a barium hydrocarbyl sulfonate.
 10. The composition of claim 9 wherein the alkanoates each have from about four to 12 carbon atoms, and the sulfonate is a barium alkaryl sulfonate.
 11. The composition of claim 10 wherein the total weight of barium and zinc alkanoates is from about 0.1 to 0.6 percent by weight, the glycol ether is present in amounts from about 0.2 to 0.5 percent by weight, the sulfonate is present in amounts from about 0.2 to 0.5 percent by weight, and the weight ratio of barium to zinc in the alkanoates is from about 8:1 to 12:1.
 12. The composition of claim 11 wherein the Group IIA metal alkanoate is barium 2-ethylhexanoate, the Group IIB metal alkanoate is zinc 2-ethylhexanoate, the ether is 1-methoxy-2-propanol, the sulfonate is a barium alkaryl sulfonate having a Molecular Weight of from about 900 to 1100, and the weight ratio of barium to zinc in the 2-ethylhexanoates is about 10:1.
 13. In the method of operating an internal combustion engine wherein a liquid hydrocarbon fuel is passed through a fuel supply system into a combustion chamber of said engine and said fuel is caused to ignite therein, the improvement comprising operating said engine on a hydrocarbon fuel containing a minor proportion of a Group IIA metal salt of an alkanoic acid branched in the alpha position, a Group IIB metal salt of an alkanoic acid branched in the alpha position, an alkyl ether of a glycol having about 3 to 10 carbon atoms and a Group IIA metal sulfonate, wherein the weight ratio of Group IIA metal to Group IIB metal in the alkanoates is from about 5 to 1 to about 30 to 1 and the weight proportions of total alkanoates and ether to sulfonate is about 1 to 3 parts of total alkanoates and about 1 to 2 parts of ether to 1 to 2 parts of sulfonate.
 14. In the method of operating a compression ignition engine wherein a diesel fuel is passed through a fuel supply system into a combustion chamber of said engine and said fuel is cauSed to ignite therein, the improvement comprising operating said engine on a diesel fuel containing a barium and a zinc alkanoate, wherein each alkanoate is branched in the alpha position, an alkyl ether of a glycol having about three to 10 carbon atoms and a barium hydrocarbyl sulfonate wherein the total weight of said alkanoates are from about 0.05 to 5 percent by weight, said ether is present in amounts from about 0.05 to 5 percent by weight, and said sulfonate is present in amounts from 0.05 to 1 percent by weight, and the weight percentages are based on the total weight of fuel mixture.
 15. The method of claim 14 wherein said fuel mixture is a diesel fuel containing barium 2-ethylhexanoate, zinc 2-ethylhexanoate, 1-methoxy-2-propanol, and a barium alkaryl sulfonate having a Molecular Weight of about 1000, wherein the weight ratio of barium to zinc in the 2-ethylhexanoates is about 10:1, the total weight of the alkanoates is from about 0.1 to 0.6 percent by weight, said ether is present in amounts from about 0.2 to 0.5 percent by weight, and said sulfonate is present in amounts from about 0.2 to 0.5 percent by weight, based on the total weight of diesel fuel mixture. 